The overall objectives of the proposed research are the development, and evaluation of a computer-based system for providing on-line monitoring and advice in the area of drug interaction. The project's general goals include determination of the magnitude of the drug interaction problem in terms of incidence and consequences, implementation of a capability for preventive intervention into the therapeutic process, and evaluation of the effects of such intervention on process and outcome of health care delivery. The project utilizes the hardware, software and pharmacological information capabilities of the MEDIPHOR drug interaction monitoring and reporting system at Stanford. This system employs a large well-documented computer data base of drug interaction information accumulated during the past 5 years by the Division of Clinical Pharmacology. In addition to its evaluation of the prototype system implemented at Stanford, a major goal of the project is implementation of the system at two nearby community hospitals in order to determine the magnitude of the drug interaction problem at those institutions, and to assess the effects of intervention into the therapeutic process there. In addition to providing test sites that are entirely separate from the site of our developmental efforts, these community hospitals offer important additional features making them especially suitable for our demonstration experiment, including an already developed functional capability for on-line acquisition of patient drug profile and laboratory test data information.